Preparing for Prevention of Huntington's Disease (PREVENT-HD)

Inclusion Criteria for HD Participants: * Estimated at low or high probability of motor diagnosis based on the multivariate risk score (MRS) * Willing to commit to two in-person assessment visits (baseline and 2-year follow-up) and remote assessments as needed * No active comorbidities (i.e. receiving stable treatment) * All medications will be allowed although the protocol will mandate documentation of medications and analyses will particularly assess potential impact of medications on outcomes (i.e., sedation of abnormal movements) * If previously measured, CAG results must be 36 or above (previous CAG is not a requirement, but this threshold will be upheld for those participants who have their CAG scores and/or have them in their medical record). Inclusion Criteria for Healthy Controls (HC): * Willing to commit to two in-person assessment visits (baseline and 2-year follow-up) and remote assessments as needed * In generally good health * IQ \> 70 * Able to undergo an MRI scan Exclusion Criteria (for all Participants): * Evidence of unstable medical or psychiatric illness (including substance abuse) * History of severe learning disability, mental retardation, or other central nervous system (CNS) disease or event (e.g., seizures, head trauma, additional neurological diagnoses) * Treatment with phenothiazine-derivative antiemetic medications such as prochlorperazine, metoclopramide, promethazine and Inapsine greater than 3 times per month * History of serious alcohol or…